Electric switch



March 25, 1930. G. H. TOVEY ET AL.

ELECTRIC SWITCH Filed Jan 5, 1928 Invenbows: George H-Toveg, Car-I Thumim,

Their Attorney.

Patented Mar. 25, 1930 UNITED STATES PATENT OFFICE GEORGE E. mom, or Lansnownn, AND cam. THUMIM, or rmannrrnm, rmm- SYLVANIA, assrenons TO GENERAL ELECTRIC COMPANY, A com-cannon or NEW YORK ELECTRIC SWITCH Application filed January 5, 1928. Serial at. 244,596.

Our invention relates to electric switches and particularly to the construction of 'the contacts thereof. It is the object of our in-:

vention to provide an improved switch 'con-.

tact structure wherein the contacts are pressed,

together with a yielding force which is substantially uniform over their faces and wherein the contacts engage and disengage each other simultanenously at substantially all points of their contact area.

Our invention will be better understood from the following description takeninconnection with the accompanying drawing, and its scope will be pointed out;in the appended claims.

Referrin to the drawing, Fig. 1 shows an oil switch in, longitudinal section equipped with contacts involving our invention; Figs. 2 and 3 are elevation and sectional'views respectively of the contacts shown in Fig. 1 drawn to a larger scale.

In the drawin where we have shown for example a switch of the liquid'break type, the oil tank 1 having the supporting ring or base 2 is partially filled with insulating liquid 3 such as oil and is closed at the top by the cover or top 4'. \Vithin this top is the switch operating mechanism comprisin the operating rod 5, levers 6 and 7, link 8 an toggle 9, the last being connected through shaft 10 to the external arm 11 through which the switch is operated by means not shown. Extending down through the top 4 are the insulator bushings 12 in which are the conducting studs 13. Secured to the inner end of each stud is one of the fixed contacts 14, a pair of which is adapted to be bridged by the wedge-shaped yoke or bridging member 15 carried by the operating rod 5.

Each fixed contact 14 comprises the base portion 18 into which the stud 13 is threaded and securely clamped by the bolt 19 and nut 20. For engaging the movable wedgeshaped contact we have provided a plurality of yielding contact fingers each comprising the inclined plate 22 havin 'a flat contact face adapted to be engaged by the adjacent face of member 15. To the rear face of the plate 22 there is secured, as for example by the extruded rivets 23, the box-like securing member 24 and the flexible pigtail connection .25. Member 24 is convenientl formed of sheet metal one portion of whic forms the base through which extend the rivets 23 and other portions are bent up to form the sides and top. Each contact plate 22 is supported from the base 18 by a rigid member 27, the lower end of which loosely fits in and extends through the member 24. A central stud or rivet 28 has its ends engaging respectively the bottom and top of member 24 and its intermediate portion passing loosely through an aperture in the supporting member 27. At the outer end of rivet 28 is the rounded head 29 and bearing upon this head is the leaf spring 30. Bolt 31 serves to firmly secure flexible connector 25, supporting member 27 and spring 30 to the base 18. The rigid supporting member 27 is shown as having a bend intermediate itsends whereby the lower portion is parallel with the adj acent face of the movable contact 15. In the open circuit position of the switch-the spring 30 yieldingly holds the top of member 24 against the outer face of supporting member 27 and the rivet 28 being centrally arranged, the contact plate 22 is maintained with its contact face parallel to the adjacent contact .face of contact-15. In the closing movement of the switch, contacts 15 and 22 initially engage over their entire contact faces. Continued upward travel of '15 pushes contact 22 laterally against spring 30. During this movement it will be noted that the opposing force of the sprin is applied'at a single point and approximate y centrally of the contact 22 which together with the fact that this contact is loosely held by the supporting member 27 results in a self-alinement of the cooperating contacts at all times during their engagement.

The opening in the lower end of the supporting member 27 through which extends the rivet 28 is only slightly larger than the rivet or enough to permit the necessary freedom of movement of contact plate 22 for alinement with contact 15. It will be noted that when the contacts of this switch engage and slide over each other to their final position and likewise in being disengaged there In accordance with our construction, contact 22, although supported to have the desired freedom of movement to permit self-alinement, is restrained within definite limits in the line of motion of contact 15 and flexible connection 25 is relieved of stresses arising from normal contact friction, momentum of moving parts, roughness of contact surface due -to pitting, welding together of the contacts, etc.

For the purpose of limiting the upwardmovement of contact 15 in the event of over- .travel thereof the base 18is provided with the stop extension 33. The fixed contact 14 includes also an arcing contact finger 34' which is arranged atone side of the aforedescribed fingers and is constructed to be the first to make and last to break contact with What we claim as new and desire to secure by Letters Patent of the United States, is:

1. An electric switch having cooperating relatively movable contacts. a base member having a rigid member fixed thereto for supporting one of said contacts, means fixed to said one contact loosely connecting the same with the member and a resilient member fixed to said base member and having a point contact with said means arranged centrally thereof.

2. An electric switch comprising a wedge contact and a base member having a plurality of cooperating self-alining contact fingers, each including a contact plate, a rigid supporting member therefor fixed to said base, means fixed to the plate loosely connectin the plate with the supporting member an a spring having a point contact with said means tending to hold the plate in a predetermined position.

lel to theface ofthe wedge contact in the open circuit position. 5. An electric switch comprising cooperating contacts adapted to have sliding engagement with each other, a base member having fixed thereto a rigid support for one of said contacts, means fixed to said one contact loosely connecting the same with the support, a flexible current connection to said one contact and means for yieldingly pressing'the contacts together, said support and contact connecting means permitting selfa'linement of the corresponding contact and limiting the movement thereof in the direction of movement of the cooperating contact.

6. An electric switch comprising a movable wedge-shaped contact, a cooperating fixed contact comprising a base, a plurality of rigid supporting members secured thereto, a plurality of contact plates, each having a flexible connection with said base, said plates being arranged in pairs forming a wedgeshaped opening therebetween to receive the movable contact, means loosely connecting the respective plates and supporting memberscomprising a member having a portion overlying the supporting member and having a rounded extension, and a leaf spring secured to said base at one end and engaging said extension at the other end. In witness whereof, we have hereunto set our hands this 3rd day of January, 1928.

GEORGE H. TOVEY. CARL THUMIM.

3. An electric switch comprising a contact wedge and a cooperating contact comprising a base member, a plurality of self-alining contact fingers secured thereto, each finger comprising a contact plate, a rigid supporting member therefor, means loosely connecting the member with the plate, and a leaf spring secured by the base member and having a point contact with said means.

4. An electric switch comprising a movable wedge contact, a cooperating fixed contact comprising inclined plates, a rigid supporting member for each plate, means loosely connecting each plate with its supporting member. having a central rounded portion, and a spring engaging each portion, said means engaging said member on opposite sides of the rounded portion under the influence of the spring to retain the plate paral- 

